convert an old XT (or AT) keyboard to USB using a pro micro (or teensy) with an atmega32u4
reset pro micro into bootloader mode: https://github.com/nicholaskell/Arduino_Loader/blob/master/reset.py
https://github.com/tmk/tmk_keyboard/blob/master/tmk_core/doc/build.md
https://deskthority.net/workshop-f7/xt-at-ps2-terminal-to-usb-converter-with-nkro-t2510.html
tbc.